The broad aim of this project is to understand carbonaceous materials which have a wide range of applications (e.g. biosensors to measure low O2 or NO concentrations in living tissue) and health consequences (environmental health and safety). ENDOR and EPR are used to study the naturally occurring free radicals in coal, coal extracts, synthetic coal, and coal model systems. The identity, concentration and reactivity of the radicals and the nature of their environment are characterized.